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'{{Infobox storage medium | name = Compact Disc Digital Audio | logo = [[File:CDDAlogo.svg|frameless]] | image = | caption = | type = [[Optical disc]] | encoding = 2 channels of [[Linear pulse code modulation|LPCM]] audio, each [[signedness|signed]] 16-[[bit]] values sampled at 44100 [[Hertz|Hz]] | capacity = up to 74–80 minutes (up to 24 minutes for mini 8 cm CD) | read = Semiconductor laser (780 nm wavelength) | write = | standard = IEC 60908 | owner = [[Sony]] & [[Philips]] | use = Audio storage | extended from = | extended to = }} {{optical disc authoring}} '''Compact Disc Digital Audio''' ('''CDDA''' or '''CD-DA''') is the [[standardization|standard]] format for audio [[compact disc]]s. The standard is defined in the ''Red Book'', one of a series of "[[Rainbow Books]]" (named for their binding colors) that contain the [[technical specification]]s for all CD formats. == Standard == The ''Red Book'' specifies the physical parameters and properties of the CD, the optical "stylus" parameters, deviations and error rate, modulation system ([[eight-to-fourteen modulation]], EFM) and error correction facility ([[cross-interleaved Reed–Solomon coding]], CIRC), and the eight [[Compact disc subcode|subcode channels]]. These parameters are common to all [[compact discs]] and used by all logical formats, such as [[CD-ROM]]. The standard also specifies the form of [[digital audio]] encoding: 2-channel [[Signedness|signed]] 16-[[bit]] [[Linear pulse code modulation|Linear PCM]] sampled at [[44,100 Hz]]. Although rarely used, the specification allows for discs to be mastered with a form of [[Emphasis (telecommunications)|emphasis]]. The first edition of the ''Red Book'' was released in 1980 by [[Philips]] and [[Sony]];<ref name="BBC"/><ref name="Auto45-1"/> it was adopted by the Digital Audio Disc Committee and ratified as [[International Electrotechnical Commission|IEC]] 60908 (published in 1987).<ref name="Auto45-2"/> The second edition of IEC 60908 was published in 1999<ref name="Auto45-3"/> and it cancels and replaces the first edition, amendment 1 (1992) and the corrigendum to amendment 1. The IEC 60908 however does not contain all the information for extensions that is available in the Red Book, such as the details for [[CD-Text]], [[CD+G]] and [[CD+EG]].<ref>[http://www.edocpublish.com/resources-2/specifications/cd-logos/ Approved Compact Disc Logo configurations]</ref><ref>[http://www.ccs.neu.edu/home/bchafy/cdb/info/info.html Specs for Freeware Developers]</ref> The standard is not freely available and must be licensed. It is available from [[Philips]] and the [[International Electrotechnical Commission|IEC]]. {{As of|2013}}, Philips outsources licensing of the standard to Adminius, which charges {{US$|100}} for the ''Red Book'', plus {{US$|50}} each for the ''Subcode Channels R-W'' and ''CD Text Mode'' annexes.<ref name="philips_red_book">{{cite web|url=https://www.lscdweb.com/ordering/cd_products.html |title=CD Products |work=lscdweb.com |accessdate=2013-05-24}}</ref> {{As of|2013}}, the IEC 60908 document is available as a PDF download for {{US$|372}}.<ref name="Auto45-14"/> == Audio format == The audio contained in a CD-DA consists of two-channel [[Signedness|signed]] 16-[[bit]] [[Linear pulse code modulation|Linear PCM]] sampled at [[44,100 Hz]]. === Sample rate === {{Details|44.1 kHz}} The [[sampling rate]] is adapted from that attained when recording digital audio on a [[PAL]] (or [[NTSC]]) [[videotape]] with a [[PCM adaptor]], an earlier way of storing digital audio.<ref name="Auto45-4"/> An audio CD can represent frequencies up to 22.05&nbsp;kHz, the [[Nyquist frequency]] of the 44.1&nbsp;kHz sample rate. The selection of the sample rate was based primarily on the need to reproduce the audible frequency range of 20–20,000&nbsp;Hz (20&nbsp;kHz). The [[Nyquist–Shannon sampling theorem]] states that a sampling rate of more than twice the maximum frequency of the signal to be recorded is needed, resulting in a required rate of at least 40&nbsp;kHz. The exact sampling rate of 44.1&nbsp;kHz was inherited from a method of converting digital audio into an analog video signal for storage on [[U-matic|U-matic video tape]], which was the most affordable way to transfer data from the recording studio to the CD manufacturer at the time the CD specification was being developed. The device that converts an analog audio signal into PCM audio, which in turn is changed into an analog video signal is called a [[PCM adaptor]]. This technology could store six samples (three samples per stereo channel) in a single horizontal line. A standard [[NTSC]] video signal has 245 usable lines per field, and 59.94 fields/s, which works out to be 44,056 samples/s/stereo channel. Similarly, [[PAL]] has 294 lines and 50 fields, which gives 44,100 samples/s/stereo channel. This system could store 14-bit samples with some error correction, or 16-bit samples with almost no error correction.{{CN|date=April 2014}} There was a long debate over the use of 14-bit (Philips) or 16-bit (Sony) [[Quantization (sound processing)|quantization]], and 44,056 or 44,100 samples/s (Sony) or approximately 44,000 samples/s (Philips). When the Sony/Philips task force designed the Compact Disc, Philips had already developed a 14-bit [[Digital-to-analog converter|D/A converter]] (DAC), but Sony insisted on 16-bit. In the end, 16 bits and 44.1 kilosamples per second prevailed. Philips found a way to produce 16-bit quality using its 14-bit DAC by using four times [[oversampling]].<ref name=Immink /> === Pre-emphasis === {{main|Emphasis (telecommunications)}} Some CDs are mastered with pre-emphasis, an artificial boost of high audio frequencies. The pre-emphasis improves the apparent signal-to-noise ratio by making better use of the channel's dynamic range. On playback, the player applies a de-emphasis filter to restore the frequency response curve to an overall flat one. Pre-emphasis time constants are 50µs or 15µs, and a binary flag in the disc [[subcode]] instructs the player to apply de-emphasis filtering if appropriate. Playback of such discs in a computer or 'ripping' to [[WAV|wave files]] typically does not take into account the pre-emphasis, so such files play back with a distorted frequency response.{{cn|date=March 2015}} == Storage capacity and playing time == The creators of the CD originally aimed at a playing time of 60&nbsp;minutes with a disc diameter of 100&nbsp;mm (Sony) or 115&nbsp;mm (Philips).<ref name=Immink2/> Sony vice-president [[Norio Ohga]] suggested extending the capacity to 74 minutes to accommodate [[Wilhelm Furtwängler]]'s recording of [[Ludwig van Beethoven]]'s [[Symphony No. 9 (Beethoven)|Symphony No. 9]] from the 1951 [[Bayreuth Festival]].<ref name="PhilBeet"/><ref name="Auto45-6"/> The additional 14-minute playing time subsequently required changing to a 120&nbsp;mm disc. [[Kees Schouhamer Immink]], Philips' chief engineer, however, denies this, claiming that the increase was motivated by technical considerations, and that even after the increase in size, the Furtwängler recording would not have fit on one of the earliest CDs.<ref name=Immink2 /><ref name=Immink /> According to a ''[[Sunday Tribune]]'' interview,<ref name="ferguscassidy"/> the story is slightly more involved. In 1979, Philips owned [[PolyGram]], one of the world's largest distributors of music. PolyGram had set up a large experimental CD plant in [[Hannover]], Germany, which could produce huge numbers of CDs having a diameter of 115&nbsp;mm. Sony did not yet have such a facility. If Sony had agreed on the 115-mm disc, Philips would have had a significant competitive edge in the market. The long playing time of Beethoven's Ninth Symphony imposed by [[Norio Ohga|Ohga]] was used to push Philips to accept 120&nbsp;mm, so that Philips' PolyGram lost its edge on disc fabrication.<ref name="ferguscassidy"/> The 74-minute playing time of a CD, which was longer than the 22&nbsp;minutes per side<ref name="Auto45-7"/><ref name="Auto45-8"/> typical of long-playing (LP) vinyl albums, was often used to the CD's advantage during the early years when CDs and LPs vied for commercial sales. CDs would often be released with one or more bonus tracks, enticing consumers to buy the CD for the extra material. However, attempts to combine double LPs onto one CD occasionally resulted in the opposite situation in which the CD would actually offer fewer tracks than the equivalent LP{{citation needed|date=October 2014}}, though bonus tracks were also added to CD re-releases of double LPs as well{{citation needed|date=October 2014}}. Playing times beyond 74&nbsp;minutes are achieved by decreasing track pitch beyond the original ''Red Book'' standard. Most players can accommodate the more closely spaced data.<ref name="Auto45-9"/> [[Christian Thielemann]]'s live [[Deutsche Grammophon]] recording of [[Anton Bruckner|Bruckner's]] [[Symphony No. 5 (Bruckner)|Fifth]] with the [[Munich Philharmonic]] in 2004 clocks at 82:34.<ref name="Auto45-10"/> The [[Kirov Orchestra]] recording of [[Pyotr Ilyich Tchaikovsky]]'s ''The Nutcracker'' conducted by [[Valery Gergiev]] and released by Philips/PolyGram Records (catalogue number 462 114) on October 20, 1998, clocks at 81:14.{{Citation needed|date=July 2010}} The [[Mission of Burma]] compilation album ''Mission of Burma'', released in 1988 by [[Rykodisc]], previously held the record at 80:08.<ref name="Auto45-11"/> Current manufacturing processes allow an audio CD to contain up to 80 minutes (variable from one replication plant to another) without requiring the content creator to sign a waiver releasing the plant owner from responsibility if the CD produced is marginally or entirely unreadable by some playback equipment. Thus, in current practice, maximum CD playing time has crept higher by reducing minimum engineering tolerances; by and large, this has not unacceptably reduced reliability.{{citation needed|date=February 2013}} == Technical specifications == === Data encoding === Each audio sample is a [[Signedness|signed]] 16-bit [[two's complement]] [[Integer (computer science)|integer]], with sample values ranging from −32768 to +32767. The source audio data is divided into frames, containing twelve [[Sampling (signal processing)|samples]] each (six left and right samples, alternating), for a total of 192 bits (24 bytes) of audio data per frame. This stream of audio frames, as a whole, is then subjected to [[Cross-interleaved Reed–Solomon coding|CIRC]] encoding, which segments and rearranges the data and expands it with [[parity bit]]s in a way that allows occasional read errors to be detected and corrected. CIRC encoding also interleaves the audio frames throughout the disc over several consecutive frames so that the information will be more resistant to [[burst error]]s. Therefore, a physical frame on the disc will actually contain information from multiple logical audio frames. This process adds 64 bits of [[error correction]] data to each frame. After this, 8 bits of [[subcode]] or subchannel data are added to each of these encoded frames, which is used for control and addressing when playing the CD. CIRC encoding plus the subcode byte generate 33-bytes long frames, called "channel-data" frames. These frames are then modulated through [[eight-to-fourteen modulation]] (EFM), where each 8-bit word is replaced with a corresponding 14-bit word designed to reduce the number of transitions between 0 and 1. This reduces the density of [[Compact disc#Physical details|physical pits]] on the disc and provides an additional degree of error tolerance. Three "merging" bits are added before each 14-bit word for disambiguation and synchronization. In total there are 33 × (14 + 3) = 561 bits. A 27-bit word (a 24-bit pattern plus 3 merging bits) is added to the beginning of each frame to assist with synchronization, so the reading device can locate frames easily. With this, a frame ends up containing 588 bits of "channel data" (which are decoded to only 192 bits music). The frames of channel data are finally written to disc physically in the form of [[Compact disc#Physical details|pits and lands]], with each pit or land representing a series of zeroes, and with the transition points—the edge of each pit—representing 1. A Red Book-compatible CD-R has pit-and-land-shaped spots on a layer of organic dye instead of actual pits and lands; a laser creates the spots by altering the reflective properties of the dye. === Data structure=== [[File:CD Diagra.001.jpg|thumb|This image of a [[CD-R]] demonstrates some of the visible features of an audio CD, including the lead-in, program area, and lead-out. A microscopic spiral of digital information begins near the disc's middle and ends near the edge. Data-free areas of the disc and silent portions of the spiral reflect light differently, sometimes allowing track boundaries to be seen]] The audio data stream in an audio CD is continuous, but has three parts. The main portion, which is further divided into playable audio tracks, is the ''program area''. This section is preceded by a ''lead-in'' track and followed by a ''lead-out'' track. The lead-in and lead-out tracks encode only silent audio, but all three sections contain [[subcode]] data streams. The lead-in's subcode contains repeated copies of the disc's Table Of Contents (TOC), which provides an index of the start positions of the tracks in the program area and lead-out. The track positions are referenced by absolute [[timecode]], relative to the start of the program area, in MSF format: minutes, seconds, and fractional seconds called ''frames''. Each timecode frame is one seventy-fifth of a second, and corresponds to a block of 98 channel-data frames—ultimately, a block of 588 pairs of left and right audio samples. Timecode contained in the subchannel data allows the reading device to locate the region of the disc that corresponds to the timecode in the TOC. The TOC on discs is analogous to the [[partition table]] on [[hard drive]]s. Nonstandard or corrupted TOC records are abused as a form of [[CD/DVD copy protection]], in e.g. the [[key2Audio]] scheme. ==== Tracks ==== {{main|Track (CD)#Audio tracks}} The largest entity on a CD is called a track. A CD can contain up to 99 tracks (including a data track for [[Mixed Mode CD|mixed mode discs]]). Each track can in turn have up to 100 indexes, though players which handle this feature are rarely found outside of [[pro audio]], particularly radio broadcasting{{Citation needed|date=October 2012}}. The vast majority of songs are recorded under index 1, with the [[pre-gap]] being index 0. Sometimes [[hidden track]]s are placed at the end of the last track of the disc, often using index 2 or 3. This is also the case with some discs offering "101 sound effects", with 100 and 101 being indexed as two and three on track 99. The index, if used, is occasionally put on the track listing as a decimal part of the track number, such as 99.2 or 99.3. ([[Information Society (band)|Information Society]]'s ''[[Hack (album)|Hack]]'' was one of very few CD releases to do this, following a release with an equally obscure CD+G feature.) The track and index structure of the CD were carried forward to the [[DVD]] format as title and chapter, respectively. Tracks, in turn, are divided into timecode frames (or sectors), which are further subdivided into channel-data frames. ==== Frames and timecode frames ==== {{main|Track (CD)#Sector structure}} The smallest entity in a CD is a channel-data ''frame'', which consists of 33 bytes and contains six complete 16-bit stereo samples: 24 bytes for the audio (two bytes × two channels × six samples = 24 bytes), eight CIRC error-correction bytes, and one [[Compact Disc subcode|subcode]] byte. As described in the "Data encoding" section, after the EFM modulation the number of bits in a frame totals 588. On a ''Red Book'' audio CD, data is addressed using the ''MSF scheme'', with [[timecode]]s expressed in minutes, seconds and another type of ''frames'' (mm:ss:ff), where one frame corresponds to 1/75th of a second of audio: 588 pairs of left and right samples. This timecode frame is distinct from the 33-byte channel-data frame described above, and is used for time display and positioning the reading laser. When editing and extracting CD audio, this timecode frame is the smallest addressable time interval for an audio CD; thus, track boundaries only occur on these frame boundaries. Each of these structures contains 98 channel-data frames, totaling 98 × 24 = 2,352 bytes of music. The CD is played at a speed of 75 frames (or sectors) per second, thus 44,100 samples or 176,400 bytes per second. In the 1990s, [[CD-ROM]] and related [[ripping|Digital Audio Extraction]] (DAE) technology introduced the term ''[[CD-ROM#CD-ROM format|sector]]'' to refer to each timecode frame, with each sector being identified by a sequential [[integer]] number starting at zero, and with tracks aligned on sector boundaries. An audio CD sector corresponds to 2,352 bytes of decoded data. The ''Red Book'' does not refer to sectors, nor does it distinguish the corresponding sections of the disc's data stream except as "frames" in the MSF addressing scheme. The following table shows the relation between tracks, timecode frames (sectors) and channel-data frames: {| class="wikitable" |- ! Track level | colspan = 6 | Track N |- ! Timecode frame or sector level | colspan = 3 | Timecode frame or sector 1 (2,352 b of data) | Timecode frame or sector 2 (2,352 b of data) | ... |- ! Channel-data frame level | Channel-data frame 1 (24 b of data) | ... | Channel-data frame 98 (24 b of data) | ... | ... |} === Bit rate === The audio [[bit rate]] is 1,411.2 [[Data rate units#Kilobit per second|kbit/s]] (as 2 channels × 44,100 samples per second per channel × 16 bits per sample = 1,411,200 [[Bits per second|bit/s]] = 1,411.2 kbit/s). Likewise, in a computer, audio data coming in from a CD drive is accessed by sectors, each sector being 2,352 bytes, and with 75 sectors containing 1 second of audio, for the same bit rate of 2,352 × 75 = 176.4 [[kibibyte|KiB]]/s (1,411.2 kbit/s). In comparison, the bit rate of a "1×" [[CD-ROM]] is defined as 2,048 bytes per sector × 75 sectors per second = 150 [[kibibyte|KiB]]/s (1,228.8 kbit/s). The undecoded channel-data rate for a ''Red Book'' audio CD is 4.3218 [[megabit|Mbit/s]], with 2.0338 Mbit/s being the rate of the undecoded audio and subcode. === Data access from computers === Unlike on a [[DVD]] or [[CD-ROM]], there are no "[[computer file|file]]s" on a ''Red Book'' audio CD; there are only the physical pits and lands, which in turn represent a single encoded data stream, which ultimately represents one continuous stream of [[LPCM]] audio data, and a parallel, smaller set of 8 [[subcode]] data streams. Computer [[operating system]]s, however, may provide access to an audio CD as if it contains files. For example, [[Microsoft Windows|Windows]] represents the CD's Table of Contents as a set of [[Compact Disc Audio track]] (CDA) files, each file containing indexing information, not audio data. In a process called [[ripping]], digital audio extraction software can be used to read CD-DA audio data and store it in files. Common [[audio file format]]s for this purpose include [[WAV]] and [[Audio Interchange File Format|AIFF]], which simply preface the LPCM data with a short [[header (computing)|header]]; [[FLAC]], [[Apple Lossless|ALAC]], and [[Windows Media Audio#Windows Media Audio Lossless|Windows Media Audio Lossless]], which compress the LPCM data in ways that conserve space yet allow it to be restored without any changes; and various [[lossy compression|lossy]], [[perceptual audio coder|perceptual coding]] formats like [[MP3]] and [[Advanced Audio Coding|AAC]], which modify and compress the audio data in ways that irreversibly change the audio, but that exploit features of human hearing to make the changes difficult to discern. == Format variations == Recording publishers have created CDs that violate the ''Red Book'' standard. Some do so for the purpose of [[copy protection|copy prevention]], using systems like [[Copy Control]]. Some do so for extra features such as [[DualDisc]], which includes both a [[CD]] layer and a [[DVD]] layer whereby the CD layer is much thinner, 0.9&nbsp;mm, than required by the ''Red Book'', which stipulates a nominal 1.2&nbsp;mm, but at least 1.1&nbsp;mm. Philips and many other companies have stated that including the Compact Disc Digital Audio logo on such non-conforming discs may constitute [[trademark]] infringement. Either in anticipation or in response, recent{{When|date=August 2012}} copy-protected CDs bear stickers and warnings that the CD is not standard and may not play in all CD players, and no longer display the long-familiar logo.{{Citation needed|date=March 2013}} [[Super Audio CD]] was a standard published in 1999 that aimed to provide better audio quality in CDs, but it never became very popular. [[DVD Audio]], an advanced version of the audio CD, emerged in 1999.<ref name="Auto45-12"/> The format was designed to feature audio of higher fidelity. It applies a higher sampling rate and used 650&nbsp;nm lasers. == Copyright issues == {{Main|Compact Disc and DVD copy protection}} There have been moves by the [[recording industry]] to make audio CDs (Compact Disc Digital Audio) unplayable on computer [[CD-ROM]] drives, to prevent the copying of music. This is done by intentionally introducing errors onto the disc that the embedded circuits on most stand-alone audio players can automatically compensate for, but which may confuse CD-ROM drives. Consumer rights advocates as of October 2001 pushed to require warning labels on compact discs that do not conform to the official Compact Disc Digital Audio standard (often called the [[#Standard|Red Book]]) to inform consumers which discs do not permit full [[fair use]] of their content. In 2005, [[Sony BMG Music Entertainment]] was criticised when a copy protection mechanism known as [[Extended Copy Protection]] (XCP) used on some of their audio CDs automatically and surreptitiously installed copy-prevention software on computers (see [[2005 Sony BMG CD copy protection scandal]]). Such discs are not legally allowed to be called CDs or Compact Discs because they break the Red Book standard governing CDs, and Amazon.com for example describes them as "copy protected discs" rather than "compact discs" or "CDs". == See also == * [[Extended Copy Protection]] * [[Digital rights management]] * [[Four-channel compact disc digital audio]] * [[Linear pulse-code modulation]] * [[WAV]] * [[Audio Interchange File Format|AIFF]] == References == {{reflist|30em|refs= <ref name="BBC">{{ cite web | url = http://news.bbc.co.uk/2/hi/technology/6950933.stm | title = How the CD was developed | publisher = BBC News | date = August 17, 2007 | accessdate = 2007-08-17 }}</ref> <ref name="Auto45-1">{{ cite web |url=http://www.philipsmuseumeindhoven.nl/phe/products/e_cd.htm |title= Philips Compact Disc | work = Philips Historical Products |accessdate=2010-10-06 }}</ref> <ref name="Auto45-2">{{ citation |url=http://www.iec.ch/dyn/www/f?p=103:105:0::::FSP_SEARCH_ORG_ID,FSP_SEARCH_AND,FSP_SEARCH_QUOTE,FSP_SEARCH_OR,FSP_SEARCH_NONE,FSP_SEARCH_DOCREF,FSP_SEARCH_STAGECODE,FSP_SEARCH_HEAD,FSP_SEARCH_PUBPROJREF,FSP_SEARCH_DATERANGE,FSP_SEARCH_DATEFROM,FSP_SEARCH_DATETO,FSP_REQUEST:%2C%2C%2C%2C%2C%2C%2C%2C60908%2C0%2C%2C%2C5 |title=IEC 60908 ed 1.0 - IEC search|accessdate=2011-07-28 }}</ref> <ref name="Auto45-3">{{ citation |url=http://webstore.iec.ch/preview/info_iec60908%7Bed2.0%7Db.pdf |title=IEC 60908 ed. 2.0 - preview |format=PDF |author=IEC |accessdate=2011-07-28 }}</ref> <ref name="Auto45-4">[http://stason.org/TULARC/pc/cd-recordable/2-35-Why-44-1KHz-Why-not-48KHz.html 2-35<nowiki>]</nowiki> Why 44.1KHz? Why not 48KHz?]</ref> <ref name="PhilBeet">{{ cite web | url = http://www.marantzphilips.nl/The_cd_laser/ | title = Beethoven's Ninth Symphony of Greater Importance than Technology | author = Philips | accessdate = 2007-02-09 }}</ref> <ref name="Auto45-6">{{ cite web | url = http://www.aes.org/historical/store/oralhistory/?code=OHP-016-DVD | title = AES Oral History Project: Kees A.Schouhamer Immink | author = AES | accessdate = 2008-07-29 }}</ref> <ref name="ferguscassidy">{{ cite news | url = http://www.ferguscassidy.ie/ethos-23-Oct-2005.html | title = Great Lengths | last = Cassidy | first = Fergus | format = reprint | publisher = ''[[Sunday Tribune]]'' | date = 2005-10-23| accessdate = 2007-12-21}}</ref> <ref name="Auto45-7">{{cite book |last=Hoffmann |first=Frank |last2=Ferstler |first2=Howard |title=Encyclopedia of Recorded Sound |publisher=[[CRC Press]] |year=2005| page=1289 |isbn=978-0-415-93835-8}}</ref> <ref name="Auto45-8">Goldmark, Peter. ''Maverick inventor; My Turbulent Years at CBS.'' New York: Saturday Review Press, 1973.</ref> <ref name="Auto45-9">{{ cite web |url=http://www.cdrfaq.org/faq03.html#S3-8 |title=CD-Recordable FAQ |author=Andy McFadden |date=2010-01-09 |accessdate=2010-12-30}}</ref> <ref name="Auto45-10">{{ cite web|url=http://www.audaud.com/article.php?ArticleID=410|title=BRUCKNER: Symphony No. 5 in B flat major&nbsp;— Munich Philharmonic/Christian Thielemann&nbsp;— DGG|publisher=audaud.com|accessdate=2011-04-06}}</ref> <ref name="Auto45-11">{{ cite web|url=http://www.discogs.com/Mission-Of-Burma-Mission-Of-Burma/release/1129709|title=Mission of Burma 1988 Rykodisc compilation information|publisher=discogs.com|accessdate=2011-01-18|quote=This Rykodisc release was the first compact disc to contain 80 minutes of music; 78 minutes had previously been the longest length possible to encode on a CD.}}</ref> <ref name="Auto45-12">{{ cite web|last=Taylor|first=Jim|title=DVD FAQ|url=http://www.dvddemystified.com/dvdfaq.html|work=DVD Demystified|accessdate=21 August 2012 }}{{dead link|date=March 2013}}</ref> <ref name="Auto45-14">[http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC+60908+Ed.+2.0+b%3A1999 IEC 60908 Ed. 2.0 b:1999 Audio recording&nbsp;– Compact disc digital audio system]</ref> <ref name="Immink">{{ cite journal | url = http://www.exp-math.uni-essen.de/~immink/pdf/cdstory.htm | title = The CD Story | author = Kees A. Schouhamer Immink | journal = Journal of the AES | volume = 46 | pages = 458–465 | year = 1998 | accessdate = 2007-02-09 }}</ref> <ref name="Immink2">{{ cite journal | url = http://www.exp-math.uni-essen.de/~immink/pdf/beethoven.htm | title = Shannon, Beethoven, and the Compact Disc | author = Kees A. Schouhamer Immink | journal = IEEE Information Theory Newsletter | pages = 42–46 | year = 2007 | accessdate = 2007-12-12 }}</ref> }} == External links == * [http://www.ip.philips.com/licensing/program/15 Philips' Audio Standards licensing info] * [http://webstore.iec.ch/webstore/webstore.nsf/artnum/023623 IEC 60908 publication info] * [http://wiki.multimedia.cx/index.php?title=PCM#Red_Book_CD_Audio MultimediaWiki article about PCM and ''Red Book'' CD Audio] {{Rainbow Books}} {{CD}} [[Category:Rainbow Books]] [[Category:Audio storage]] [[Category:1980 introductions]] [[Category:Joint ventures]] [[Category:IEC 60908]]'